<?php

// code by Ollie Brown, 2008
// see http://blog.olvr.org/2008/08/last-fm-google-charts/

/****************************************************************************************************
You are free to take this code, use it and modify it. I’m making no guarantees about the code though,
and I wont be held responsible for any consequences of the use or misuse of it. You should read,
understand and evaluate what the code does before you implement it yourself. You should also stick
to the Google Chart API usage policy, the Audioscrobbler licence and any other applicable terms.
If you do use this code, a link back to the parent page would be appreciated. Have fun!
****************************************************************************************************/

class lastfmChart {
	
	var $dataFile = '';			// location of xml file

	var $chartDataType = 'pc';		// type of data needed for chart (percentage [pc] or number [num])
	var $chartDataPoints = '15';		// number of data points

	var $chartTitle = 'Chart Title';
	var $chartType = 'pie';
	var $chartSize = '400x400';
	var $chartColors = '';

	var $chartLabels = '';
	var $chartValues = '';
	var $maxPlays = 0;			// highest number of plays

	var $chartURI = 'http://chart.apis.google.com/chart?';

	function lastfmChart() {
	}

	function setDataFile($value) {
		$this->dataFile = $value;
	}

	function setDataPoints($value) {
		$this->chartDataPoints = $value;
	}

	function setTitle($value) {
		$this->chartTitle = $value;
	}

	function setSize($value) {
		$this->chartSize = $value;
	}

	function setColors($value) {
		$this->chartColors = $value;
	}

	function setMaxPlays($value) {
		$this->maxPlays = $value;
	}

	function setType($value) {
	// set the type of chart and some other required / default parameters
		
		switch ($value) {
			case 'pie':
				$value = 'p';
				$type = 'pc';		// pie chart requires percentage values
				$size = '550x200';
				break;
			case 'bar':
				$value = 'bhg';
				$type = 'num';		// bar chart requires absolute numbers
				$size = '400x400';
				break;
			default:
				$value = $value;
				$type = $type;
				break;
		}
		
		$this->chartType = $value;
		$this->chartDataType = $type;
		$this->setSize($size);
	}

	function getData($xml) {
	// get data from xml
		
		// read in xml
		$music = simplexml_load_file($xml);
		
		// initiate some variables
		$listens = array();
		$tot_plays = 0;
		$counter = 0;
		
		// blank labels and values
		$this->chartLabels = '';
		$this->chartValues = '';
		
		// string for encoding - these 62 characters have increasing value
		$simpleEncoding = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
		
		// for each artist in the xml
		foreach ($music->artist as $artist) { 
			
			// add the artist name to the label string up to the number of data points required
			if ($counter < $this->chartDataPoints) {
				$this->chartLabels .= $artist->name . '|';
			}
			
			// store the number of plays for this artist, add the plays to the total
			// and increment the counter
			$plays[$counter] = $artist->playcount;
			$tot_plays += $artist->playcount;
			$counter++;
			
		} 
		
		// for each plays value
		foreach ($plays as $play) {
			
			// get a number that works with charts
			if ($this->chartDataType == 'pc') {
				$play = $play / $tot_plays * 61;
			} elseif ($this->chartDataType == 'num') {
				$play = $play / $plays[0] * 61;
			}
			
			// encode these values
			$this->chartValues .= substr($simpleEncoding,$play,1);
			
		}
		
		// trim values to number of data points required
		$this->chartValues = substr($this->chartValues, 0, $this->chartDataPoints);
		
		// trim trailing separator from labels and encode for use in a url
		$this->chartLabels = substr($this->chartLabels, 0, strlen($this->chartLabels) - 1);
		$this->chartLabels = urlencode($this->chartLabels);
		
		// if this is a bar chart, reverse the chart values
		if ($this->chartType == 'bhg') {
			$this->chartValues = strrev($this->chartValues);
		}
		
		// store the highest number of plays
		$this->setMaxPlays($plays[0]);
		
	}

	function doChart() {
		
		// get the data
		$this->getData($this->dataFile);
		
		// start appending to url
		$this->chartURI .= 'chtt=' . urlencode($this->chartTitle) . '&cht=' . $this->chartType;
		$this->chartURI .= '&chs=' . $this->chartSize . '&chco=' . $this->chartColors;
		$this->chartURI .= '&chd=s:' . $this->chartValues;
		
		// chart type specifics
		if ($this->chartType == 'p') {
			$this->chartURI .= '&chl=' .  $this->chartLabels;
		} elseif ($this->chartType == 'bhg') {
			$this->chartURI .= '&chxt=x,y&chxl=0:|0|' . $this->maxPlays . '|1:|' . $this->chartLabels;
		}
		
		// output into img tag
		echo '<img src="' . $this->chartURI . '" alt="' . $this->chartTitle . '"/>';
		
	}

}